Biology subjects

Rosene, D. L.

Publications and source records attributed to Rosene, D. L..

5 recordsLinked to original sources

bioRxiv2026

Multimodal characterization of putative pan-inhibitory viral constructs in macaque monkeys

Transgenic approaches and validated viral vector toolboxes have advanced our understanding of how inhibitory neurons shape cognition and motor control in mice and other rodents. However, such advances have been elusive in non-human primates (NHPs). While many studies demonstrate expression of reporter proteins, few studies have provided clear quantitative evidence of whether these viral constructs can be reliably used for assessment of in vivo and in vitro function in primates, which, in turn, has hindered widespread adoption by NHP researchers. Here, we characterize putative pan-inhibitory cell targeting vectors engineered with regions from the Dlx5-6 intergenic domain. Pan-inhibitory viral vectors are attractive because they enable ground-truth optotagging and modulation of multiple inhibitory subtypes in the same animal and, when combined with machine learning approaches, enable cell-type classifiers for NHPs. We combined in vivo anesthetized electrophysiological recordings, in vitro slice electrophysiology, and immunohistochemistry across seven rhesus macaque monkeys to assess the specificity, completeness and efficacy of three constructs in multiple sensory and higher-order association cortices. The vectors reliably restricted transgene expression to inhibitory neurons (81-97%). However, of the local GABAergic neurons only 32-64% expressed the transgene, depending on the construct. This incompleteness arose in part from uneven coverage across subtypes, with strong transgene expression in parvalbumin-positive interneurons (~60-90%), sparse expression in calbindin-positive interneurons (~1-7%), and near-complete avoidance of calretinin-positive interneurons. A construct pairing DLX2.0 with ChrimsonR was excellent for in vivo optotagging, while h56D paired with bReaChES most effectively suppressed neural activity in vivo. In the slice, activating terminals of transgene-expressing neurons optically evoked inhibitory currents in coupled pyramidal neurons confirming transsynaptic functionality of these constructs and their use for inhibitory circuit-specific synaptic assessments and manipulation. Collectively, the results provide rigorous functional characterization, and quantitative guidance for NHP researchers seeking to deploy GABAergic cell-type-specific tools in their experiments.

neuroscience↗

bioRxiv2026

Molecular anatomy of the entorhinal cortex

The entorhinal cortex (EC) is critical for episodic memory formation and is the epicenter of neurofibrillary tangle formation in Alzheimer's disease. Its cytoarchitectonic and functional heterogeneity has been recognized for decades, but the molecular underpinnings of this heterogeneity are still relatively uncharted. While many features of the region appear to be conserved between rodents and primates, very little is known about the conservation of the molecular identity of EC neurons. Here we perform single-nucleus RNAseq (snRNAseq) of the mouse EC and use in situ hybridization, as well as publicly available transcriptomics data, to enhance the understanding of the heterogeneity of neuron types present in the area. While the well-known dichotomy between lateral and medial EC is evident in superficial layers of EC, we highlight that the medioventral region of EC forms a different population from the caudomedial section. We identify molecular correlates for the previously described parcellation of lateral EC, and show that, at least in layer IIa, subterritories of EC are not separated by abrupt borders but rather form smooth gradients. Lastly, we show that both lateral vs. medial ECIIa markers, and markers that reveal finer grain heterogeneity within ECIIa have conserved patterns of expression in macaque, highlighting the high degree of homology between the two species. Overall this molecular atlas of the mouse EC with some comparative elements is a resource for anatomically-informed molecular studies of the EC and lays the groundwork for mechanistic studies of selective neuronal vulnerability of the region in the context of AD.

neuroscience↗

bioRxiv2026

Connectional neuroanatomy of U-fibers in the rhesus monkey brain

The superficial white matter (SWM), the region of white matter immediately beneath the gray matter-white matter (GM-WM) border, contains short cortico-cortical association fibers that interconnect neighboring cortical regions. The SWM is estimated to comprise the majority of axons in the cerebral white matter and is thus thought to play a major role in cortical information processing. Despite this prominence, and growing attention in the diffusion MRI (dMRI) field, the connectional organization of the SWM remains poorly defined. A major component of the SWM is U-shaped fiber bundles, classically depicted in brain dissections as bundles beneath sulci that interconnect adjacent gyri. The prevailing view, from both brain dissection and dMRI, considers U-fibers to be ubiquitous elements of the SWM that form symmetric connections between corresponding portions of adjacent gyri beneath all sulci, and they are routinely reconstructed in tractography as a layer of short association connections. However, their actual prevalence and organization in the primate brain have never been systematically evaluated with experimental tract tracing. To address this gap, we analyzed 28 archival macaque tract-tracing cases in which anterograde tracers were injected on gyri adjacent to major cortical sulci (intraparietal, central, principal, superior temporal), all of which have clear anatomical correspondences to sulci in the human cerebral cortex. Several organizational principles emerged. First, although short association fibers were present in every case, U-fibers - operationally defined as labeled fibers that left the injection site, passed beneath a sulcus, and terminated on the adjacent gyrus - were only observed in a minority of cases. Second, U-fiber incidence was sulcus-dependent: U-fibers were consistently present beneath the principal and central sulci, but uncommon beneath the intraparietal and superior temporal sulci. Third, when present, U-fibers did not follow a uniform trajectory - some took a course symmetric and orthogonal to the sulcus, whereas others followed oblique trajectories to more distant regions. In addition to U-fibers, we identified shorter association fiber bundles that terminated on the sulcal bank proximal to the injection, or on the opposing bank after they crossed the fundus of the sulcus, evidence that the SWM contains multiple classes of short association fiber bundles rather than a single canonical U-fiber system. We further identified a consistent 200-300 {micro}m band of white matter beneath cortical layer 6 that contained exclusively short association fibers on approach to their cortical terminations and was selectively avoided by deeper long cortico-cortical pathways. This band was present across all examined sulci, suggesting that it is a conserved feature of the cortical white matter. Notably, U-fibers were found both within this band and in the white matter below. We also identified deeper fiber bundles that adopted a U-shaped course beneath a sulcus but did not interconnect adjacent gyri. Thus, a U-shaped trajectory alone does not define a U-fiber. Together, these findings constitute the first systematic connectional study of cortical U-fibers in major sulci of the non-human primate brain and indicate that the white matter beneath the cortex is a highly complex system in which short association fiber bundle organization reflects the selective connectivity of the cortical areas separated by a sulcus, rather than a uniform U-fiber architecture imposed by the geometry of the overlying sulcus. These results have potential consequences for dMRI and anatomical studies of white matter and provide an anatomically grounded basis to better define SWM organization in anatomy and tractography.

neuroscience↗

bioRxiv2024

Mesenchymal Cell-Derived Extracellular Vesicles Ameliorate Age-Related Deficits in Working Memory as well as Brain MRI and CSF in vivo Biomarkers of Neurodegeneration in Rhesus Monkeys.

Normal aging in humans and non-human primates is associated with a decline in cognitive functions. Subject-wise differences in cognitive decline can be attributed to different degrees of damage to cortical white matter (WM) which is largely affected by neuroinflammation during aging. Mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) have recently been identified as a potential immunomodulatory therapeutic for brain damage and Alzheimers disease (AD) and related dementias by suppressing neuroinflammation. Here, we evaluated the efficacy of MSC-EVs for slowing or ameliorating cognitive decline during aging in rhesus monkeys, a well-studied model of normal aging that is free of extensive AD pathology. We report that late middle-aged monkeys treated with MSC-EVs every two weeks for 18 months showed improved performance on a task of spatial working memory relative to vehicle control monkeys. In addition, we used diffusion magnetic resonance imaging (MRI) and resting state functional MRI to evaluate structural white matter and functional network changes in vivo. Imaging data revealed that MSC-EV treatment preserved prefrontal and temporal WM structural integrity and large-scale functional network connectivity that are correlated with early, increased CSF levels of amyloid beta protein. Amyloid beta levels at 12 months are also correlated with improved cognitive performance at the end of the 18 months of treatment. These findings suggest that MSC-EVs can mitigate age-related cognitive decline by potentially enhancing the CSF clearance of neurodegenerative proteins, which correlates with greater WM integrity and functional brain connectivity.

neuroscience↗

bioRxiv2023

Neuronal properties of pyramidal cells in lateral prefrontal cortex of the aging rhesus monkey brain are associated with performance deficits on spatial working memory but not executive function.

Age-related declines in cognitive abilities occur as early as middle-age in humans and rhesus monkeys. Specifically, performance by aged individuals on tasks of executive function (EF) and working memory (WM) is characterized by greater frequency of errors, shorter memory spans, increased frequency of perseverative responses, impaired use of feedback and reduced speed of processing. However, how aging precisely differentially impacts specific aspects of these cognitive functions and the distinct brain areas mediating cognition are not well understood. The prefrontal cortex (PFC) is known to mediate EF and WM and is an area that shows a vulnerability to age-related alterations in neuronal morphology. In the current study, we show that performance on EF and WM tasks exhibited significant changes with age and these impairments correlate with changes in biophysical properties of L3 pyramidal neurons in lateral LPFC (LPFC). Specifically, there was a significant age-related increase in excitability of Layer 3 LPFC pyramidal neurons, consistent with previous studies. Further, this age-related hyperexcitability of LPFC neurons was significantly correlated with age-related decline on a task of WM, but not an EF task. The current study characterizes age-related performance on tasks of WM and EF and provides insight into the neural substrates that may underlie changes in both WM and EF with age.

neuroscience↗